Ovulation on CD 6, 3 days after period...

This can't be right, can it? For the past 2 cycles, I have been getting positive ovulation tests 2-3 days after my period. I feel like this can't be right. I have been using the clear blue digital opk so there is no misinterpreting the test results. I got my Mirena removed in July. Could that have something to do with it? Could anything else be causing a false positive? I'm a little lost.